Guardrail systems are widely used along heavily traveled roadways to enhance the safety of the roadway and adjacent roadside. Guardrail beams and their corresponding support posts are employed to accomplish multiple tasks. Upon vehicle impact, a guardrail acts to contain and redirect the errant vehicle.
For many years, standard heavy gauge metal guardrails known as “W-beams” have been used on the nation's roadways to accomplish these tasks and others. Named after its characteristic shape, the “W-beam” is a corrugated guardrail member that has two corrugations. The guardrail is typically anchored to the ground using support posts made of metal, wood, or a combination of both. A terminal support post is used at or near the terminal end of the guardrail system. Support posts other than the terminal support posts are termed “length-of-need” (LON) posts. LON posts support the guardrail along the intermediary portion of the guardrail system between opposing terminal ends of the guardrail system.
Wood support posts may be more readily available and more economical than metal posts in some geographical areas. In other areas, metal (e.g., steel) posts may be more readily available and more economical and may be preferred for their ease of installation using driving methods. As an additional benefit, wood support posts used in a LON or terminal portion of a guardrail system have been made to break away upon impact, thus producing a desired behavior during a collision by a vehicle at the impact site. However, in some environments, wood posts deteriorate more rapidly and alternate materials are sought.
Commonly used steel posts do not break away in the desired fashion and are not optimal for use in the guardrail system and especially not suitable for use in the terminal section of a guardrail system. Break away steel support posts that are modified to allow for failure during a collision have recently become available. Examples include a “hinged breakaway post” and the “energy absorbing breakaway steel guardrail post” described in U.S. Pat. No. 6,254,063. Many such prior attempts require substantial time, money, and resources during fabrication, modification, and/or installation.